Thin film support substrate for use in hydrogen production filter and production method of hydrogen production filter

ABSTRACT

In a through hole closing process, a metal plate is attached to one surface of a conductive base member having a plurality of through holes by the use of a magnet, in a copper plating process, a copper plating layer is formed on the conductive base member and the metal plate exposed within the through holes, from the side of the conductive base member where the metal plate is not attached, thereby to fill up the through holes, in a film forming process, a Pd alloy film is formed by plating on the surface of the conductive base member after removal of the metal plate, and in a removal process, the copper plating layer is removed by selective etching, thereby to produce a hydrogen production filter that is used in a reformer of a fuel cell so as to be capable of stably producing high purity hydrogen gas.

This application is a divisional application of U.S. application Ser.No. 10/491,888, filed Apr. 15, 2004 now U.S. Pat. No. 7,112,287, whichis a 371 of PCT/JP03/09330 filed on Jul. 23, 2003.

TECHNICAL FIELD

The present invention relates to a production method of a hydrogenproduction filter and, in particular, relates to a production method ofa hydrogen production filter for steam-reforming hydrocarbon fuel ofvarious kinds to produce hydrogen rich gas for a fuel cell.

Further, the present invention relates to a thin film support substratefor use in a hydrogen production filter, particularly a hydrogenproduction filter for steam-reforming hydrocarbon fuel of various kindsto produce hydrogen rich gas for a fuel cell, and a production method ofa hydrogen production filter using such a thin film support substrate.

BACKGROUND ART

In recent years, attention has been paid to using hydrogen as fuelbecause there is no generation of global warming gas such as carbondioxide from the aspect of the global environmental protection and theenergy efficiency is high. Particularly, inasmuch as fuel cells candirectly convert hydrogen into electric power and enable high energyconversion efficiency in cogeneration systems utilizing generated heat,attention has been paid thereto. Heretofore, the fuel cells have beenemployed under a special condition such as in the space development orthe ocean development. Recently, however, the development has beenadvanced toward using them as automobile or household distributed powersupplies. Further, fuel cells for portable devices have also beendeveloped.

The fuel cell is a power generator wherein hydrogen rich gas obtained byreforming hydrocarbon fuel such as natural gas, gasoline, butane gas, ormethanol, and oxygen in the air are reacted electrochemically, therebyto directly produce electricity. In general, the fuel cell comprises areformer for producing hydrogen rich gas by steam-reforming hydrocarbonfuel, a fuel cell body for producing electricity, a converter forconverting the produced dc electricity into alternating current, and soforth.

Depending on an electrolyte used in the fuel cell body, a reactionmanner, and so forth, there are five kinds in those fuel cells, i.e. aphosphoric acid fuel cell (PAFC), a molten carbonate fuel cell (MCFC), asolid oxide fuel cell (SOFC), an alkaline fuel cell (AFC), and a solidpolymer fuel cell (PEFC). Among them, the solid polymer fuel cell (PEFC)has a favorable condition in that an electrolyte is solid, as comparedwith other fuel cells such as the phosphoric acid fuel cell (PAFC) andthe alkaline fuel cell (AFC).

However, since the solid polymer fuel cell (PEFC) uses platinum as acatalyst and an operating temperature thereof is low, there is adrawback that the electrode catalyst is poisoned with a small quantityof CO, and degradation in performance is remarkable particularly in ahigh current density region. Therefore, it is necessary to produce highpurity hydrogen by reducing a concentration of CO contained in reformedgas (hydrogen rich gas) produced in a reformer, to about 10 ppm.

As one of methods for removing CO from the reformed gas, there has beenused a membrane separation method employing a Pd alloy film as a filter.Unless there are pinholes, cracks, or the like in the film, the Pd alloyfilm can theoretically transmit only hydrogen and, by setting thereformed gas side under high-temperature and high-pressure conditions(e.g. 300° C., 3 to 100 kg/cm²), it transmits hydrogen to the lowhydrogen partial pressure side.

In the foregoing membrane separation method, inasmuch as thetransmission speed of hydrogen is inversely proportional to a filmthickness, reduction in film thickness is required. However, in terms ofthe mechanical strength, reduction in film thickness up to about 30 μmis a limit for a Pd alloy film alone, and therefore, when a Pd alloyfilm having a thickness of about ten-odd micrometers is used, a supportmember having a porous structure is disposed on the low hydrogen partialpressure side of the Pd alloy film. However, since the Pd alloy film andthe support member are mounted in a reformer as separate members, therehas been a problem that the operability for achieving excellent sealingis bad, and durability of the Pd alloy film is not sufficient due tooccurrence of friction between the Pd alloy film and the support member.

For solving the foregoing problem, there has been developed a filter inwhich a Pd alloy film and a support member of a porous structure areunified together using an adhesive. However, there has been a problemthat it is necessary to remove the adhesive from the Pd alloy filmlocated at hole portions of the support member, and therefore, theproduction processes are complicated. Further, since it is used underhigh-temperature and high-pressure conditions in the reformer,degradation of the adhesive is unavoidable, resulting in insufficientdurability of the filter.

Moreover, there is a limit to the magnitude of opening diameters of holeportions in the support member for ensuring a required strength of thesupport member, and therefore, there is also a limit about increasing anarea of the Pd alloy film that is effective for transmission ofhydrogen, so that improvement in hydrogen transmission efficiency hasbeen impeded.

DISCLOSURE OF THE INVENTION

Therefore, it is an object of the present invention to provide aproduction method of a hydrogen production filter that is used in areformer of a fuel cell so as to be capable of stably producing highpurity hydrogen gas.

For accomplishing such an object, the present invention is configured tocomprise a through hole closing step of attaching a metal plate to onesurface of a conductive base member having a plurality of through holesby the use of a magnet, a copper plating step of forming a copperplating layer on the conductive base member and said metal plate exposedwithin the through holes, from the side of said conductive base memberwhere said metal plate is not attached, thereby to fill up said throughholes, a film forming step of forming a Pd alloy film by plating on thesurface of said conductive base member after removal of said metalplate, and a removal step of removing said copper plating layer byselective etching.

Further, the present invention is configured to comprise a sticking stepof sticking an insulating film to one surface of a conductive basemember having a plurality of through holes, a copper plating step offorming a copper plating layer on a surface of said conductive basemember where said insulating film is not stuck, so as to fill up saidthrough holes, a film forming step of forming a Pd alloy film by platingon the surface of the conductive base member after removal of saidinsulating film, and a removal step of removing said copper platinglayer by selective etching.

Further, the present invention is configured to comprise a filling stepof filling a resin material into through holes of a conductive basemember having the plurality of through holes, an underlayer forming stepof forming a Pd alloy film on one surface of said conductive base memberby either of electroless plating and a vacuum film forming method,thereby to form a conductive underlayer, a film forming step of forminga Pd alloy film by plating on said conductive underlayer, and a removalstep of dissolving and removing only said resin material.

Further, the present invention is configured to comprise an etching stepof forming predetermined resist patterns on both surfaces of aconductive base member, and etching said conductive base member fromboth sides using said resist patterns as masks to form a plurality ofthrough holes, a film forming step of forming a Pd alloy film byelectrolytic plating so as to close the inside of said through holes ofsaid conductive base member, and a removal step of removing said resistpatterns.

In the present invention as described above, even if the Pd alloy filmis thin, since it is fixed to the conductive base member with a highstrength so as to be unified together, durability of the filter becomesextremely high. Therefore, according to the present invention, the Pdalloy film formed by plating is fixed to the conductive base memberhaving a plurality of through holes, with a high strength so as to beunified together, and no adhesive is used, and thus, it is excellent inheat resistance and can be used under high-temperature and high-pressureconditions. Further, even if the Pd alloy film is reduced in thicknessto increase the hydrogen transmission efficiency, it is possible toproduce a hydrogen production filter that is excellent in durability andfurther in operability upon mounting thereof to a reformer, and soforth.

It is an object of the present invention to provide a thin film supportsubstrate enabling a hydrogen production filter that is used in areformer of a fuel cell so as to be capable of stably producing highpurity hydrogen gas, and a production method of a hydrogen productionfilter using such a thin film support substrate.

For accomplishing such an object, the present invention is configured tobe a thin film support substrate for use in a hydrogen productionfilter, comprising a metal substrate, a plurality of columnar convexportions formed on one surface of said metal substrate, and a pluralityof through holes formed at a portion where said columnar convex portionsare not formed, so as to pierce the metal substrate, wherein an area ofthe columnar convex portion non-formed portion occupying on the columnarconvex portion formed side is within the range of 20 to 90%.

Further, the present invention is configured to comprise, in aproduction method of a hydrogen production filer using the foregoingthin film support substrate, a disposing step of disposing an insulatingfilm on a surface of said thin film support substrate where the columnarconvex portions are formed, so as to fix the insulating film to the topsurfaces of said columnar convex portions, an underlayer forming step offorming a conductive underlayer by electroless plating on said thin filmsupport substrate excluding the top surfaces of said columnar convexportions and on a fixation side of said insulating film, a copperplating step of forming a copper plating layer on said conductiveunderlayer so as to fill up a space formed between the metal substrateof said thin film support substrate and said insulating film, and theinside of the through holes of said thin film support substrate, a filmforming step of forming a Pd alloy film by plating on a surface formedby the top surfaces of said columnar convex portions and said copperplating layer after removal of said insulating film, and a removal stepof removing said copper plating layer by selective etching.

Further, the present invention is configured to comprise, in aproduction method of a hydrogen production filer using the foregoingthin film support substrate, a disposing step of disposing an insulatingfilm on a surface of said thin film support substrate which is on anopposite side relative to a surface where the columnar convex portionsare formed, a copper platen step of forming a copper plating layer onthe surface of said thin film support substrate where the columnarconvex portions are formed, so as to fill up the inside of said throughholes and cover said columnar convex portions, a flattening step offlat-removing said copper plating layer so as to expose top surfaces ofsaid columnar convex portions and form the same flat surface with saidtop surfaces, a film forming step of forming a Pd alloy film by platingon the flat surface formed by the top surfaces of said columnar convexportions and said copper plating layer, and a removal step of removingthe copper plating layer by selective etching after removal of saidinsulating film.

Further, the present invention is configured to comprise, in aproduction method of a hydrogen production filer using the foregoingthin film support substrate, a resin layer forming step of forming aresin layer on a surface of said thin film support substrate where thecolumnar convex portions are formed, so as to fill up the inside of thethrough holes and cover said columnar convex portions, a flattening stepof flat-removing said resin layer so as to expose top surfaces of saidcolumnar convex portions and form the same flat surface with said topsurfaces, an underlayer forming step of forming a conductive underlayerby either of electroless plating and a vacuum film forming method on theflat surface formed by the top surfaces of said columnar convex portionsand said resin layer, a film forming step of forming a Pd alloy film byplating on said conductive underlayer, and a removal step of dissolvingand removing only said resin layer.

Further, the present invention is configured to comprise, in aproduction method of a hydrogen production filer using the foregoingthin film support substrate, a film forming step of forming a Pd alloyfilm by plating on one surface of a metal base member that is capable ofselective etching relative to said thin film support substrate, adiffusion joining step of disposing said metal base member on a surfaceof said thin film support substrate where the columnar convex portionsare formed, by diffusion joining said Pd alloy film to the top surfacesof the columnar convex portions, and a removal step of removing saidmetal base member by selective etching.

According to the present invention, since the thin film supportsubstrate is provided with the metal substrate, even if the area ratioof the columnar convex portion non-formed portion occupying on thecolumnar convex portion formed side is increased, the thin film supportsubstrate has a high strength, and therefore, the area of the Pd alloyfilm effective for the hydrogen transmission can be increased so thatthe hydrogen transmission efficiency can be improved. Further, in theproduction method of the present invention using such a thin filmsupport substrate of the present invention, since the Pd alloy filmformed by plating is fixed to the top surfaces of the columnar convexportions of the thin film support substrate having the through holes,with a high strength so as to be unified together, it is possible toproduce a hydrogen production filter that has a large effective hydrogentransmission area, that is excellent in heat resistance and can be usedunder high-temperature and high-pressure conditions because no adhesionis used, that is excellent in durability even if the Pd alloy film isreduced in thickness to increase the hydrogen transmission efficiency,and that is excellent in operability upon mounting thereof to areformer, and so forth.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A to 1D are process diagrams showing one embodiment of aproduction method of a hydrogen production filter of the presentinvention.

FIGS. 2A to 2D are process diagrams showing another embodiment of aproduction method of a hydrogen production filter of the presentinvention.

FIGS. 3A to 3D are process diagrams showing another embodiment of aproduction method of a hydrogen production filter of the presentinvention.

FIGS. 4A to 4D are process diagrams showing another embodiment of aproduction method of a hydrogen production filter of the presentinvention.

FIG. 5 is a plan view showing one embodiment of a thin film supportsubstrate of the present invention.

FIG. 6 is a longitudinal sectional view, taken along line I-I, of thethin film support substrate shown in FIG. 5.

FIG. 7 is a longitudinal sectional view, taken along line II-II, of thethin film support substrate shown in FIG. 5.

FIG. 8 is a longitudinal sectional view, taken along line III-III, ofthe thin film support substrate shown in FIG. 5.

FIGS. 9A to 9E are process diagrams showing one embodiment of aproduction method of a hydrogen production filter of the presentinvention.

FIGS. 10A to 10E are process diagrams showing another embodiment of aproduction method of a hydrogen production filter of the presentinvention.

FIGS. 11A to 11E are process diagrams showing another embodiment of aproduction method of a hydrogen production filter of the presentinvention.

FIGS. 12A to 12C are process diagrams showing another embodiment of aproduction method of a hydrogen production filter of the presentinvention.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described.

FIGS. 1A to 1D are process diagrams showing one embodiment of aproduction method of a hydrogen production filter of the presentinvention.

In the production method of the present invention, at the outset, in athrough hole closing process, a metal plate 14 is attached, by the useof a magnet 15, to one surface 12 a of a conductive base member 12having a plurality of through holes 13, thereby to close the throughholes 13 (FIG. 1A). As a material of the conductive base member 12,there can be cited one having conductivity such as an Fe—Cr materialbeing ferrite stainless that is fixable to a magnet like SUS430, and athickness can be suitably set within the range of 20 to 500 μm,preferably 50 to 300 μm. The through holes 13 are formed by means suchas etching via a predetermined resist pattern, punching, laserprocessing, or the like. The opening size of each through hole 13 can beset within the range of 10 to 500 μm, preferably 50 to 300 μm, and thesum of opening areas of the plurality of through holes 13 relative tothe whole area of the conductive base member 12 can be set within therange of 5 to 75%, preferably 10 to 50%. Incidentally, the foregoingopening size is a diameter when an opening shape of the through hole 13is circular, while it is the mean between a maximum opening portion anda minimum opening portion when an opening shape thereof is polygonal orthe like. Hereinafter, the same shall apply in the present invention.

As the foregoing metal plate 14, there can be used one havingconductivity and being ferromagnetic or soft magnetic, and there can becited an Fe—Cr material or an Fe—C material being ferrite stainless thatis fixable to a magnet like SUS430, or an Fe—Cr—Ni material or the likethat is not fixable to a magnet like SUS304. A thickness of such a metalplate 14 can be suitably set taking into account a material thereof,magnetic charge of the using magnet 15, or the like, and can be set to,for example, about 20 to 500 μm.

As the magnet 15 that is used for attaching the metal plate 14 onto theconductive base member 12, a permanent magnet, an electromagnet, or thelike in the form of a film or plate can be used.

Then, in a copper plating process, copper plating is applied to aconductive base member surface 12 b where the metal plate 14 is notattached, so as to form a copper plating layer 16 on the conductive basemember surface 12 b and on the metal plate 14 exposed in the throughholes 13, thereby filling up the through holes 13 (FIG. 1B). This copperplating process aims for filling up the through holes 13 with the copperplating, and therefore, there is no particular limitation to a thicknessand a shape of the copper plating layer 16 formed on the conductive basemember surface 12 b.

Then, in a film forming process, the foregoing metal plate 14 and magnet15 are removed, and a Pd alloy film 17 is formed by plating on theconductive base member surface 12 a after the removal (FIG. 1C). Theformation of the Pd alloy film 17 can be achieved by a method in which aPd alloy film is directly formed by electrolytic plating, a method inwhich thin films of respective components composing a Pd alloy arestacked in layers on the conductive base member surface 12 a byelectrolytic plating or electroless plating, then a heat treatment isimplemented to form a Pd alloy film by diffusion of the components, orthe like. For example, by forming Pd in a thickness of 10 μm by plating,forming thereon Ag in a thickness of 1 μm by plating, then applying aheat treatment at 250° C. for 10 minutes, a Pd alloy can be obtained. Onthe other hand, a heat treatment may be implemented after carrying outmultilayer plating of three layers composed of Pd/Ag/Pd, four layerscomposed of Pd/Ag/Pd/Ag, or the like. A thickness of the Pd alloy thinfilm 17 can be set to 0.5 to 30 μm, preferably about 1 to 15 μm.

Incidentally, by applying Ni strike plating or the like to theconductive base member surface 12 a before forming the Pd alloy film 17,it is possible to increase adhesion relative to the Pd alloy film 17 tobe formed. A thickness of such Ni strike plating can be set within therange of, for example, 0.01 to 0.5 μm.

Then, in a removal process, the copper plating layer 16 is removed byselective etching, thereby to obtain a hydrogen production filter 11(FIG. 1D). The selective etching can be carried out by spraying,dipping, blowing, or the like using an ammonia etching liquid.

In the hydrogen production filter 11 thus produced, the Pd alloy film 17is fixed to the conductive base member 12 with a high strength, andtherefore, even if the Pd alloy film is reduced in thickness forincreasing the hydrogen transmission efficiency, it is a filter withremarkably high durability. Further, since no adhesive is used, it isexcellent in heat resistance and can be used under high-temperature andhigh-pressure conditions, and further, it is also excellent inoperability such as mounting thereof to a reformer.

FIGS. 2A to 2D are process diagrams showing another embodiment of aproduction method of a hydrogen production filter of the presentinvention.

In the production method of the present invention, at the outset, in asticking process, an insulating film 24 is stuck onto one surface 22 aof a conductive base member 22 having a plurality of through holes 23(FIG. 2A). As a material of the conductive base member 22, there can becited austenite or ferrite stainless such as SUS304 or SUS430, or thelike, and a thickness can be suitably set within the range of 20 to 500μm, preferably 50 to 300 μm. The through holes 23 are formed by meanssuch as etching via a predetermined resist pattern, punching, laserprocessing, or the like. The opening size of each through hole 23 can beset within the range of 10 to 500 μm, preferably 50 to 300 μm, and thesum of opening areas of the plurality of through holes 23 relative tothe whole area of the conductive base member 22 can be set within therange of 5 to 75%, preferably 10 to 50%. Incidentally, the foregoingopening size is a diameter when an opening shape of the through hole 23is circular, while it is the mean between a maximum opening portion anda minimum opening portion when an opening shape thereof is polygonal orthe like. Hereinafter, the same shall apply in the present invention.

As the foregoing insulating film 24, a film of resin such aspolyethylene terephthalate, polypropylene, or polycarbonate can be used.A thickness of such an insulating film 24 can be suitably set takinginto account a material, electrical insulation performance, a filmstrength, and so forth, and can be set to, for example, about 30 to 300μm. Sticking of the insulating film 24 onto the conductive base member22 can be carried out by a method of using a polyamide or otheradhesive, a method of utilizing thermal adhesiveness of the insulatingfilm, or the like.

Then, in a copper plating process, copper plating is applied to aconductive base member surface 22 b where the insulating film 24 is notstuck, so as to form a copper plating layer 25 to thereby fill up thethrough holes 23 (FIG. 2B). This copper plating process aims for fill upthe through holes 23 with the copper plating, and therefore, there is noparticular limitation to a thickness and a shape of the copper platinglayer 25 formed on the conductive base member surface 22 b.

Then, in a film forming process, the foregoing insulating film 24 isremoved, and a Pd alloy film 26 is formed by plating on the conductivebase member surface 22 a after the removal (FIG. 2C). The removal of theinsulating film 24 can be carried out by peeling or dissolution.Further, the formation of the Pd alloy film 26 can be achieved by amethod in which a Pd alloy film is directly formed by electrolyticplating, a method in which thin films of respective components composinga Pd alloy are stacked in layers on the conductive base member surface22 a by electrolytic plating or electroless plating, then a heattreatment is implemented to form a Pd alloy film by diffusion of thecomponents, or the like. For example, by forming Pd in a thickness of 10μm by plating, forming thereon Ag in a thickness of 1 μm by plating,then applying a heat treatment at 900° C. for 10 hours, a Pd alloy canbe obtained. On the other hand, a heat treatment may be implementedafter carrying out multilayer plating of three layers composed ofPd/Ag/Pd, four layers composed of Pd/Ag/Pd/Ag, or the like. A thicknessof the Pd alloy thin film 26 to be formed can be set to 0.5 to 30 μm,preferably about 1 to 15 μm.

Incidentally, for example, by applying Ni strike plating to theconductive base member surface 22 a, it is possible to increase adhesionrelative to the Pd alloy film 26 to be formed. A thickness of such Nistrike plating can be set within the range of, for example, 0.01 to 0.1μm.

Then, in a removal process, the copper plating layer 25 is removed byselective etching, thereby to obtain a hydrogen production filter 21(FIG. 2D). The selective etching can be carried out by spraying,dipping, blowing, or the like using an ammonia etching liquid.

In the hydrogen production filter 21 thus produced, the Pd alloy film 26is fixed to the conductive base member 22 with a high strength, andtherefore, even if the Pd alloy film is reduced in thickness forincreasing the hydrogen transmission efficiency, it is a filter withremarkably high durability. Further, since no adhesive is used, it isexcellent in heat resistance and can be used under high-temperature andhigh-pressure conditions, and further, it is also excellent inoperability such as mounting thereof to a reformer.

FIGS. 3A to 3D are process diagrams showing another embodiment of aproduction method of a hydrogen production filter of the presentinvention.

First, in a filling process, a resin material 34 is filled in aplurality of through holes 33 provided in a conductive base member 32(FIG. 3A). A material and a thickness of the conductive base member 32can be the same as those of the foregoing conductive base member 22, anda forming method, dimensions, and a formation density of the throughholes 33 can also be the same as those of the foregoing through holes23. Further, the conductive base member 32 may be applied with, forexample, Ni strike plating after the formation of the through holes 33,thereby to increase adhesion relative to a Pd alloy film formed in asubsequent process. A thickness of such Ni strike plating can be setwithin the range of, for example, 0.01 to 0.1 μm.

The foregoing resin material can exhibit stable resistance inlater-described underlayer forming process and film forming process andcan be surely dissolved/removed in a removal process and, for example,novolak resist resin or the like can be used therefor. For filling sucha resin material into the through holes 33, a method such as squeezingor the like can be employed.

Then, in the underlayer forming process, a Pd alloy film is formed onone surface of the conductive base member 32 in which the resin material34 is filled in the through holes 33, thereby to form a conductiveunderlayer 35 (FIG. 3B). This underlayer forming process aims for givingconductivity to exposed surfaces of the resin material 34 filled in thethrough holes 33, and a thickness of the conductive underlayer 35 to beformed can be set within the range of 0.01 to 0.2 μm. The Pd alloy filmto be the conductive underlayer 35 can be formed by electroless plating,or may be formed by a vacuum film forming method such as sputtering orvacuum deposition.

Then, in the film forming process, a Pd alloy film 36 is formed on theconductive underlayer 35 by plating (FIG. 3C). The formation of this Pdalloy film 36 can be achieved by a method in which a Pd alloy film isdirectly formed by electrolytic plating, a method in which thin films ofrespective components composing a Pd alloy are stacked in layers on theconductive underlayer 35 by electrolytic plating or electroless plating,then a heat treatment is implemented to form a Pd alloy film bydiffusion of the components, or the like. A thickness of the Pd alloythin film 36 to be formed can be set to 0.5 to 30 μm, preferably about 1to 15 μm.

Then, in the removal process, only the resin material 34 is dissolved tobe removed, thereby to obtain a hydrogen production filter 31 (FIG. 3D).The dissolution/removal of the resin material 34 can be carried out byspraying, dipping, or the like using a solvent such as acetone, methylethyl ketone, methyl isobutyl ketone, or the like, a desmear solution(manufactured by Shipley Corporation), or the like depending on theresin material to be used.

In the hydrogen production filter 31 thus produced, the Pd alloy film 36is fixed to the conductive base member 32 with a high strength via theconductive underlayer 35, and therefore, even if the Pd alloy film isreduced in thickness for increasing the hydrogen transmissionefficiency, it is a filter with remarkably high durability. Further,since no adhesive is used, it is excellent in heat resistance and can beused under high-temperature and high-pressure conditions, and further,it is also excellent in operability such as mounting thereof to areformer.

FIGS. 4A to 4D are process diagrams showing another embodiment of aproduction method of a hydrogen production filter of the presentinvention.

In the production method of the present invention, in an etchingprocess, at the outset, resist patterns 44 a and 44 b having a pluralityof small opening portions are formed on both surfaces of a conductivebase member 42 (FIG. 4A). The small opening portions of the resistpattern 44 a confront the small opening portions of the resist pattern44 b, respectively, via the conductive base member 42, and opening areasof the mutually confronting small opening portions may be equal to eachother, or one of them, for example, the opening area of the smallopening portion of the resist pattern 44 b, may be set greater. Theshapes and sizes of the small opening portions of such resist patterns44 a and 44 b can be suitably set taking into account an etchingcondition, a material and a thickness of the conductive base member 42,and so forth. The material and thickness of the conductive base member42 can be the same as those of the foregoing conductive base member 22.Further, the resist patterns 44 a and 44 b can be each formed byapplying a material selected from conventionally known positive andnegative photosensitive resist materials, exposing it via apredetermined mask, and developing it.

Then, by etching the conductive base member 42 using the foregoingresist patterns 44 a and 44 b as masks, a plurality of fine throughholes 43 are formed in the conductive base member 42 (FIG. 4B). Theetching of the conductive base member 42 can be carried out by spraying,dipping, blowing, or the like by the use of an etching liquid of ironchloride, copper chloride, or the like. The opening size on the side ofa conductive base member surface 42 a and the opening size on the sideof a conductive base member surface 42 b, of each through hole 43 formedin the conductive base member 42 by the etching can be set within therange of 10 to 500 μm, preferably 50 to 300 μm, and the sum of openingareas of the plurality of through holes 43 relative to the whole area ofthe conductive base member 42 can be set within the range of 5 to 75%,preferably 10 to 50%. Incidentally, upon etching the conductive basemember 42 from both surfaces using the resist patterns 44 a and 44 b asmasks, a projected portion 43 a is generally formed at a substantiallycentral portion of an inner wall surface of each formed through hole 43.Therefore, when such a projected portion 43 a exists, the foregoingopening area of the through hole 43 is an opening area at the projectedportion 43 a.

Then, in a film forming process, Pd alloy films 46 are formed byelectrolytic plating so as to close the inside of the through holes 43of the conductive base member 42 (FIG. 4C). The formation of the Pdalloy films 46 can be achieved, using the resist patterns 44 a and 44 bas masks, according to a method in which Pd alloy films are directlyformed by electrolytic plating, a method in which thin films ofrespective components composing a Pd alloy are formed by electrolyticplating, then a heat treatment is implemented to form Pd alloy films bydiffusion of the components, or the like. In the formation of such a Pdalloy film 46, when the projected portion 43 a exists at thesubstantially central portion of the inner wall surface of the throughhole 43 formed in the foregoing etching process, the current densityincreases at the projected portion 43 a so that the Pd alloy film isformed so as to close the projected portion 43 a. A thickness of the Pdalloy thin film 46 to be formed can be set to 0.5 to 30 μm, preferablyabout 1 to 15 μm. Further, by applying Ni strike plating to the insideof the through holes 43 of the conductive base member 42 before formingthe foregoing Pd alloy films, it is possible to increase adhesionrelative to the Pd alloy films. A thickness of such Ni strike platingcan be set within the range of, for example, 0.01 to 0.1 μm.

Then, in a removal process, the resist patterns 44 a and 44 b areremoved to thereby obtain a hydrogen production filter 41 (FIG. 4D). Theremoval of the resist patterns 44 a and 44 b can be carried out using asodium hydroxide solution or the like.

In the hydrogen production filter 41 thus produced, the Pd alloy films46 are fixed to the conductive base member 42 with a high strength so asto close the through holes 43, and therefore, even if the Pd alloy filmsare reduced in thickness for increasing the hydrogen transmissionefficiency, it is a filter with remarkably high durability. Further,since no adhesive is used, it is excellent in heat resistance and can beused under high-temperature and high-pressure conditions, and further,it is also excellent in operability such as mounting thereof to areformer.

FIG. 5 is a plan view showing one embodiment of a thin film supportsubstrate of the present invention, FIG. 6 is a longitudinal sectionalview, taken along line I-I, of the thin film support substrate shown inFIG. 5, FIG. 7 is a longitudinal sectional view, taken along line II-II,of the thin film support substrate shown in FIG. 5, and FIG. 8 is alongitudinal sectional view, taken along line III-III, of the thin filmsupport substrate shown in FIG. 5. In FIGS. 5 to 8, a thin film supportsubstrate 51 comprises a metal substrate 52, a plurality of columnarconvex portions 53 formed in predetermined positions of one surface ofthe metal substrate 52, and a plurality of through holes 54 formed inpredetermined positions of a portion 52 a where the columnar convexportions 53 are not formed, so as to pierce the metal substrate 52. Anoccupying area of the columnar convex portion non-formed portion 52 a onthe side where the columnar convex portions 53 are formed, is within therange of 20 to 90%, preferably 30 to 85%. When the area of the columnarconvex portion non-formed portion 52 a is less than 20%, an effect ofincreasing an area of a Pd alloy film effective for the hydrogentransmission does not become sufficient, while, when it exceeds 90%,supporting of the hydrogen transmission film is impeded to lowerdurability of a hydrogen production filer, which is not preferable.

A material of the metal substrate 52 forming the thin film supportsubstrate 51 may be, for example, austenite or ferrite stainless such asSUS304 or SUS430. A thickness of the metal substrate 52 (a thickness atthe columnar convex portion non-formed portion 52 a) can be suitably setwithin the range of 20 to 300 μm. If the thickness of the metalsubstrate 52 is less than 20 μm, the strength of the thin film supportsubstrate 51 becomes insufficient, while, if it exceeds 300 μm, thereoccurs an evil influence of increase in weight, and it becomes difficultto form the through holes 54, which is not preferable.

Diameters of the columnar convex portions 53 forming the thin filmsupport substrate 51 can be each set within the range of 20 to 500 μm,preferably 30 to 300 μm, and the formation pitch thereof can be setwithin the range of 40 to 700 μm, preferably 60 to 520 μm, thereby toset the area of the columnar convex portion non-formed portion 52 a tooccupy 20 to 90% as described above. Further, a height of each columnarconvex portion 53 can be set within the range of 10 to 200 μm,preferably 20 to 150 μm. The columnar convex portion has a cylindricalshape in the shown example, but is not limited thereto. Such columnarconvex portions 53 can be formed by, for example, half-etching the metalsubstrate from one surface via a resist pattern having a plurality ofrequired opening portions.

An opening diameter of each through hole 54 forming the thin filmsupport substrate 51 can be set within the range of 20 to 200 μm,preferably 50 to 150 μm. On the other hand, if inner diameters of thethrough hole 54 are not uniform, the minimum inner diameter is set to bethe opening diameter. The thin film support substrate 51 of the presentinvention is formed with a Pd alloy film on top surfaces 53 a of thecolumnar convex portions 53 to thereby constitute a hydrogen productionfilter, and the side of the through holes 54 become the low hydrogenpartial pressure side. Therefore, the formation density of the throughholes 54 is sufficient as long as it is within a range not giving aninfluence on the strength of the metal substrate 52. For example, aratio of A/B per unit area between the number A of the columnar convexportions 53 and the number B of the through holes 54 can be set to about1 to 10. Such through holes 54 can be formed by, for example, etchingthe metal substrate 52 from both surfaces via resist patterns eachhaving a plurality of required opening portions.

In the shown example, the columnar convex portions 53 and the throughholes 54 are formed such that a triangle having as its vertexes thecenters of the nearest three columnar convex portions 53 forms a regulartriangle, a triangle having as its vertexes the centers of the nearestthree through holes 54 forms a regular triangle, and the vertex of oneof the regular triangles is located in a position of the center ofgravity of the other regular triangle, however, not limited thereto.

Since the foregoing thin film support substrate 51 of the presentinvention is provided with the metal substrate 52, even if the arearatio of the columnar convex portion non-formed portion 52 a occupyingon the side where the columnar convex portions 53 are formed isincreased, the required strength can be maintained, and therefore, thearea of the Pd alloy film effective for the hydrogen transmission can beincreased.

Now, description will be given about a production method of a hydrogenproduction filter of the present invention using the thin film supportsubstrate of the present invention.

FIGS. 9A to 9E are process diagrams showing one embodiment of aproduction method of a hydrogen production filter of the presentinvention using the foregoing thin film support substrate 51.

In the production method of the present invention, at the outset, in adisposing process, an insulating film 62 is disposed on the surface ofthe thin film support substrate 51 where the columnar convex portions 53are formed, so as to be fixed to the top surfaces 53 a of the columnarconvex portions 53 (FIG. 9A). As the insulating film 62, for example, afilm of resin such as polyethylene terephthalate, polypropylene, orpolycarbonate can be used. A thickness of such an insulating film 62 canbe suitably set taking into account a material, electrical insulationperformance, a film strength, and so forth, and can be set to, forexample, about 30 to 300 μm. Fixation of the insulating film 62 onto thetop surfaces 53 a of the columnar convex portions 53 can be carried outby, for example, a method of using a polyamide or other adhesive, amethod of utilizing thermal adhesiveness of the insulating film, or thelike. On the other hand, as the insulating film, a dry film resist maybe disposed. By using the dry film resist, later-described removal ofthe insulating film 62 can be carried out using a peeling liquid such asan alkaline aqueous solution and, as compared with the case of using theforegoing resin film, it is advantageous that there is no physicaldamage to the thin film support substrate 51. When a photosensitive dryfilm resist is used as the insulating film, fixation onto the topsurfaces 53 a of the columnar convex portions 53 can be carried out by amethod wherein the whole surface is exposed after roll laminating orvacuum laminating and, if necessary, hot curing is implemented, or thelike.

Then, in an underlayer forming process, a conductive underlayer 63 isformed by electroless plating on the thin film support substrate 51excluding the top surfaces 53 a of the columnar convex portions 53(including the inside of the through holes 54), and on the fixation sideof the insulating film 62 (FIG. 9B). The formation of this conductiveunderlayer 63 can be performed by electroless nickel plating,electroless copper plating, or the like, and a thickness of theconductive underlayer 63 can be set within the range of about 0.01 to0.2 μm. The condition of this electroless plating is suitably setdepending on a material of the insulating film 62 to be used.

Then, in a copper plating process, a copper plating layer 64 is formedon the conductive underlayer 63 so as to fill up spaces formed betweenthe metal substrate 52 of the thin film support substrate 51 and theinsulating film 62, and the inside of the through holes 54 of the thinfilm support substrate 51 (FIG. 9C).

Then, in a film forming process, the insulating film 62 is removed, andthereafter, a Pd alloy film 65 is formed by plating on a surface formedby the top surfaces 53 a of the columnar convex portions 53 and thecopper plating layer 64 (conductive underlayer 63) (FIG. 9D). Theremoval of the insulating film 62 can be carried out by peeling ordissolution. Further, the formation of the Pd alloy film 65 can beachieved by a method in which a Pd alloy film is directly formed byelectrolytic plating, a method in which thin films of respectivecomponents composing a Pd alloy are stacked in layers by electrolyticplating or electroless plating, then a heat treatment is implemented toform a Pd alloy film by diffusion of the components, or the like. Forexample, by forming Pd in a thickness of 10 μm by plating, formingthereon Ag in a thickness of 1 μm by plating, then applying a heattreatment at 250° C. for 10 minutes, a Pd alloy can be obtained. On theother hand, a heat treatment may be implemented after carrying outmultilayer plating of three layers composed of Pd/Ag/Pd, four layerscomposed of Pd/Ag/Pd/Ag, or the like. A thickness of the Pd alloy thinfilm 65 to be formed can be set to 0.5 to 30 μm, preferably about 1 to15 μm.

Then, in a removal process, the copper plating layer 64 (conductiveunderlayer 63) is removed by selective etching, thereby to obtain ahydrogen production filter 61 (FIG. 9E). The selective etching can becarried out by spraying, dipping, blowing, or the like using an ammoniaetching liquid.

FIGS. 10A to 10E are process diagrams showing another embodiment of aproduction method of a hydrogen production filter of the presentinvention.

First, in a disposing process, an insulating film 72 is disposed on thesurface of the thin film support substrate 51, which is on the oppositeside relative to the surface where the columnar convex portions 53 areformed (FIG. 10A). As the insulating film 72, one that is the same asthe foregoing insulating film 62 can be used, and a disposing method ofthe insulating film 72 can be the same as that of the foregoinginsulating film 62.

Then, in a copper plating process, a copper plating layer 74 is formedon the surface of the thin film support substrate 51 where the columnarconvex portions 53 are formed, so as to fill up the inside of thethrough holes 54 and cover the columnar convex portions 53 (FIG. 10B).

Then, in a flattening process, the copper plating layer 74 isflat-removed so as to expose the top surfaces 53 a of the columnarconvex portions 53 and form the same flat surface with the top surfaces53 a (FIG. 10C). The flat removal of the copper plating layer 74 can becarried out by, for example, mechanical grinding or the like.

Then, in a film forming process, a Pd alloy film 75 is formed by platingon the flat surface formed by the top surfaces 53 a of the columnarconvex portions 53 and the copper plating layer 74 (FIG. 10D). Theformation of this Pd alloy film 75 can be performed like the formationof the foregoing Pd alloy film 65.

Then, in a removal process, the insulating film 72 is removed, andthereafter, the copper plating layer 74 is removed by selective etching,thereby to obtain a hydrogen production filter 71 (FIG. 10E). Theremoval of the insulating film 72 can be carried out like the removal ofthe foregoing insulating film 62. Further, the removal of the copperplating layer 74 can also be carried out like the removal of theforegoing copper plating layer 64.

In the foregoing example, the insulating film 72 is removed in theremoval process. However, it may also be configured that the insulatingfilm 72 is removed before the flattening process and, after theflattening process, the insulating film 72 is again disposed, before thefilm forming process, on the surface of the thin film support substrate51 which is on the opposite side relative to the surface where thecolumnar convex portions 53 are formed, and then removed in the removalprocess.

FIGS. 11A to 11E are process diagrams showing another embodiment of aproduction method of a hydrogen production filter of the presentinvention.

First, in a resin layer forming process, a resin layer 82 is formed onthe surface of the thin film support substrate 51 where the columnarconvex portions 53 are formed, so as to fill up the inside of thethrough holes 54 and cover the columnar convex portions 53 (FIG. 11A).The resin layer 82 can be formed by, for example, pouring a monomersolution of thermosetting resin such as epoxy resin, bismaleimide resin,or phenol resin by squeezing or the like, and hot curing it at apredetermined curing temperature.

Then, in a flattening process, the resin layer 82 is flat-removed so asto expose the top surfaces 53 a of the columnar convex portions 53 andform the same flat surface with the top surfaces 53 a (FIG. 11B). Theflat removal of the resin layer 82 can be carried out by, for example,mechanical grinding or the like.

Then, in an underlayer forming process, a conductive underlayer 83 isformed on the flat surface formed by the tope surfaces 53 a of thecolumnar convex portions 53 and the resin layer 82, by eitherelectroless plating or a vacuum film forming method (FIG. 11C). Whenforming the conductive underlayer 83 by electroless plating, it can becarried out by electroless nickel plating, electroless copper plating,or the like, and a thickness of the conductive underlayer 83 can be setwithin the range of about 0.01 to 0.2 μm. The condition of thiselectroless plating is suitably set depending on a material of the resinlayer 82. On the other hand, when forming the conductive underlayer 83by the vacuum film forming method, a thin film of Ni, Cu, Ag, Pd, or thelike can be formed, and a thickness of this thin film can be set withinthe range of about 0.01 to 0.2 μm.

Then, in a film forming process, a Pd alloy film 85 is formed by platingon the conductive underlayer 83 (FIG. 11D). The formation of this Pdalloy film 85 can be implemented like the formation of the foregoing Pdalloy film 65.

Then, in a removal process, only the resin layer 82 is dissolved to beremoved, thereby to obtain a hydrogen production filter 81 (FIG. 11E).The removal of the resin layer 82 can be carried out using an organicsolvent or the like that can dissolve the resin layer 82. In the removalof the resin layer 82, the conductive underlayer 83 is removed so as toexpose a surface of the Pd alloy film 85 on the side of the thin filmsupport substrate 51. The removal of the conductive underlayer 83 can beimplemented by a hydrogen peroxide/sulfuric acid etching liquid when Niis used, and by an ammonia alkaline etching liquid when Cu is used. WhenAg is used, since it can be formed into an alloy with Pd due to heatdiffusion, removal thereof is not necessary.

FIGS. 12A to 12C are process diagrams showing another embodiment of aproduction method of a hydrogen production filter of the presentinvention.

First, in a film forming process, a Pd alloy film 95 is formed byplating on one surface of a metal base member 92 that is capable ofselective etching relative to the thin film support substrate 51 (FIG.12A). As the foregoing metal base member 92, copper, a copper alloy, orthe like can be used, and a thickness can be suitably set within therange of 0.05 to 0.3 mm. The formation of the Pd alloy film 95 can becarried out like the formation of the foregoing Pd alloy film 65.Incidentally, for example, by applying Ni strike plating to the metalbase member 92, it is possible to increase adhesion relative to the Pdalloy film 95 to be formed. A thickness of such Ni strike plating can beset within the range of, for example, 0.01 to 0.1 μm.

Then, in a diffusion joining process, the metal base member 92 isdisposed on the surface of the thin film support substrate 51 where thecolumnar convex portions 53 are formed, by diffusion joining theforegoing Pd alloy film 95 to the top surfaces 53 a of the columnarconvex portions 53 (FIG. 12B). The joining between the Pd alloy film 95and the top surfaces 53 a of the columnar convex portions 53 bydiffusion joining can be carried out by applying a heat treatment at 900to 1400° C. for 12 to 18 hours in a vacuum.

Then, in a removal process, the metal base member 92 is removed byselective etching, thereby to obtain a hydrogen production filter 91(FIG. 12C). When, for example, the metal base member 92 is a copper basemember, the selective etching can be carried out by spraying, dipping,blowing, or the like using an ammonia etching liquid.

Since any of the hydrogen production filters 61, 71, 81, and 91 producedas described above uses the thin film support substrate 51 of thepresent invention, the area of the Pd alloy film effective for thehydrogen transmission is large, and the Pd alloy film is fixed, with ahigh strength, to the columnar convex portions 53 of the thin filmsupport substrate 51 having a high strength. Therefore, even if the Pdalloy film is reduced in thickness for increasing the hydrogentransmission efficiency, it is a filter with remarkably high durability.Further, since no adhesive is used, it is excellent in heat resistanceand can be used under high-temperature and high-pressure conditions, andfurther, it is also excellent in operability such as mounting thereof toa reformer.

Now, the present invention will be described in further detail showingmore specific examples.

EXAMPLE 1

Production of Filter for Hydrogen Production

A SUS430 member having a thickness of 50 μm was prepared as a basemember, and a photosensitive resist material (OFPR manufactured by TokyoOhka Kogyo Co., Ltd.) was applied (film thickness: 7 μm (upon drying))to both surfaces of the SUS430 member by a dip method. Then, photomaskseach having, in a pitch of 200 μm, a plurality of circular openingportions each having an opening size (opening diameter) of 120 μm weredisposed on the foregoing resist application films, and the resistapplication films were exposed via the photomasks and developed using asodium hydrogen carbonate solution. By this, resist patterns having thecircular opening portions with the opening size (opening diameter) of120 μm were formed on both surfaces of the SUS430 member. Incidentally,the centers of the respective opening portions of the resist patternsformed on the surfaces were set to coincide with each other via theSUS430 member.

Then, the SUS430 member was etched under the following condition usingthe foregoing resist patterns as masks.

<Etching Condition> Temperature: 50° C. Iron chloride concentration: 45Baume Pressure: 3 kg/cm²

After the foregoing etching process was finished, the resist patternswere removed using a sodium hydroxide solution, and washing in water wascarried out. By this, a conductive base member was obtained wherein aplurality of circular through holes were formed in the SUS430 member.The formed through holes each had a projected portion at a substantiallycentral portion of an inner wall surface, and an opening size (openingdiameter) at the projected portion was 70 μm.

Then, a metal plate (SUS430 member) having a thickness of 200 μm wasattached to one surface of the foregoing SUS430 member by the use of aplate permanent magnet to thereby close the through holes. (hereinabove,the through hole closing process)

Then, electrolytic copper plating was carried out under the followingcondition relative to a surface of the SUS430 member where the metalplate was not attached, so as to form a copper plating layer on thesurface of the SUS430 member and on the metal plate exposed within thethrough holes, thereby filling up the through holes with the copperplating. A thickness of the copper plating layer on the surface of theSUS430 member was set to 80 μm. (hereinabove, the copper platingprocess)

<Copper Plating Condition> Copper sulfate plating bath Liquidtemperature: 30° C. Current density: 1 A/dm²

Then, the metal plate and the plate permanent magnet were removed fromthe SUS430 member, and a Pd alloy film (thickness: 8 μm) was formed byelectrolytic plating on the surface of the SUS430 member after theremoval under the following condition. (hereinabove, the film formingprocess)

<Film forming condition of Pd alloy film by electrolytic plating> Pdchloride plating bath Temperature: 40° C. Current density: 1 A/dm²

Then, the copper plating layer was removed by selective etching.(hereinabove, the removal process)

After the foregoing removal of the copper plating layer was finished,cutting into a size of 3 cm×3 cm was carried out to obtain a filter forhydrogen production.

Evaluation of Hydrogen Production Filter

The hydrogen production filter thus produced was mounted in a reformer,and a mixture of butane gas and steam was continuously supplied to thePd alloy film of the filter under high-temperature and high-pressureconditions (300° C., 10 kg/cm²), thereby to measure CO concentrationsand flow rates of hydrogen rich gas transmitted to the side of theporous base member of the filter. As a result, the CO concentrationsimmediately after the start of reforming up to a lapse of 300 hours were8 to 10 ppm which were extremely low, and the flow rates of the hydrogenrich gas were 10 L/hour, and therefore, it was confirmed that thehydrogen production filter produced by the present invention wasexcellent in durability and hydrogen transmission efficiency.

Comparative Example 1

Production of Filter for Hydrogen Production

Like in Example 1, a conductive base member was obtained by forming aplurality of through holes in a SUS430 member. Then, a Pd alloy filmhaving a thickness of 30 μm was bonded to the conductive base member viaan adhesive so as to be unified together, and thereafter, the adhesiveremaining in the through holes of the conductive base member was removedusing acetone. This unified composite was cut into a size of 3 cm×3 cmto obtain a filter for hydrogen production.

Evaluation of Hydrogen Production Filter

The filter thus produced was mounted in a reformer, and a mixture ofbutane gas and steam was supplied to the Pd alloy film of the filterunder the same condition as Example 1, thereby to measure COconcentrations and flow rates of hydrogen rich gas transmitted to theside of the porous base member of the filter. As a result, the COconcentrations were 8 to 10 ppm, which were extremely low and thusexcellent, immediately after the start of reforming up to a lapse of 300hours. However, after the lapse of 300 hours, peeling of the Pd alloyfilm was caused due to degradation of the adhesive underhigh-temperature and high-pressure conditions, and the CO concentrationwas increased to about 3% due to generation of cracks of the Pd alloyfilm or the like, and therefore, it was confirmed that durability wasbad.

EXAMPLE 2

Production of Filter for Hydrogen Production

A SUS304 member having a thickness of 50 μm was prepared as a basemember, and a photosensitive resist material (OFPR manufactured by TokyoOhka Kogyo Co., Ltd.) was applied (film thickness: 7 μm (upon drying))to both surfaces of the SUS304 member by a dip method. Then, photomaskseach having, in a pitch of 200 μm, a plurality of circular openingportions each having an opening size (opening diameter) of 120 μm weredisposed on the foregoing resist application films, and the resistapplication films were exposed via the photomasks and developed using asodium hydrogen carbonate solution. By this, resist patterns having thecircular opening portions with the opening size (opening diameter) of120 μm were formed on both surfaces of the SUS304 member. Incidentally,the centers of the respective opening portions of the resist patternsformed on the surfaces were set to coincide with each other via theSUS304 member.

Then, the SUS304 member was etched under the following condition usingthe foregoing resist patterns as masks.

<Etching Condition> Temperature: 50° C. Iron chloride concentration: 45Baume Pressure: 3 kg/cm²

After the foregoing etching process was finished, the resist patternswere removed using a sodium hydroxide solution, and washing in water wascarried out. By this, a conductive base member was obtained wherein aplurality of through holes were formed in the SUS304 member. The formedthrough holes each had a projected portion at a substantially centralportion of an inner wall surface, and an opening size (opening diameter)at the projected portion was 70 μm.

Then, an insulating film having a thickness of 200 μm was stuck to onesurface of the foregoing SUS304 member. (hereinabove, the stickingprocess)

Then, electrolytic copper plating was carried out under the followingcondition relative to a surface of the SUS304 member where theinsulating film was not stuck, so as to fill up the through holes withthe copper plating and form a copper plating layer (thickness: about 80μm) on the surface of the SUS304 member. (hereinabove, the copperplating process)

<Copper Plating Condition> Using bath: Copper sulfate plating bathLiquid temperature: 30° C. Current density: 1 A/dm²

Then, the insulating film was peeled and removed from the SUS304 member,and a Pd alloy film (thickness: 8 μm) was formed by electrolytic platingon the surface of the SUS304 member after the removal under thefollowing condition. (hereinabove, the film forming process)

<Film Forming Condition of Pd Alloy Film by Electrolytic Plating> Usingbath: Pd chloride plating bath (Pd concentration: 12 g/L) pH: 7 to 8Current density: 1 A/dm² Liquid temperature: 40° C.

Then, the copper plating layer was removed by selective etching.(hereinabove, the removal process)

After the foregoing removal of the copper plating layer was finished,cutting into a size of 3 cm×3 cm was carried out to obtain a filter forhydrogen production.

Evaluation of Hydrogen Production Filter

The hydrogen production filter thus produced was mounted in a reformer,and a mixture of butane gas and steam was supplied to the Pd alloy filmof the filter under the same condition as Example 1, thereby to measureCO concentrations and flow rates of hydrogen rich gas transmitted to theside of the porous base member of the filter. As a result, the COconcentrations immediately after the start of reforming up to a lapse of300 hours were 8 to 10 ppm which were extremely low, and the flow ratesof the hydrogen rich gas were 10 L/hour, and therefore, it was confirmedthat the hydrogen production filter produced by the present inventionwas excellent in durability and hydrogen transmission efficiency.

EXAMPLE 3

Production of Filter for Hydrogen Production

Like in Example 2, a conductive base member was obtained by forming aplurality of through holes in a SUS304 member.

Then, Ni strike plating (thickness: 0.01 μm) was applied to theforegoing SUS304 member under the following condition, and thereafter, aresin material (AZ111 manufactured by Shipley Corporation) were filledin the through holes of the foregoing SUS304 member. The filling of theresin material was performed by squeezing. (hereinabove, the fillingprocess)

<Ni Strike Plating Condition> Bath composition: Nickel chloride 300 g/LBoric acid  30 g/L pH: 2 Liquid temperature: 55 to 65° C. Currentdensity: 10 A/dm²

Then, the following pretreatment was applied to one surface of theSUS304 member in which the resin material was filled in the throughholes, and thereafter, electroless plating was carried out under thefollowing condition to form an electroless Ni plating layer (thickness:0.4 μm) on the surfaces of the resin material filled in the throughholes and on the surface of the SUS304 member, thereby to obtain aconductive underlayer. (hereinabove, the underlayer forming process)

<Pretreatment>

alkaline degreasing→washing in water→chemical etching (in ammoniumpersulfate 200 g/L aqueous solution (20° C.±5° C.))→washing inwater→acid treatment (10% dilute sulfuric acid (ordinarytemperature))→washing in water→acid treatment (30% dilute hydrochloricacid (ordinary temperature))→dipping in sensitizer added liquid(composition: 0.5 g of Pd chloride, 25 g of stannous chloride, 300 mL ofhydrochloric acid, 600 mL of water)→washing in water

<Electroless Ni Plating Condition> Bath composition: Ni sulfate 20 g/L Sodium hypophosphite 10 g/L  Lactic acid 3 g/L Sodium citrate 5 g/LSodium acetate 5 g/L pH: 4.5 to 6.0 Liquid temperature: 50 to 65° C.

Then, a Pd alloy film (thickness: 8 μm) was formed by electrolyticplating on the foregoing conductive underlayer under the followingcondition. (hereinabove, the film forming process)

<Film Forming Condition of Pd Alloy Film by Electrolytic Plating> Usingbath: Pd chloride plating bath (Pd concentration: 12 g/L) pH: 7 to 8Current density: 1 A/dm² Liquid temperature: 40° C.

Then, the resin material filled in the through holes was dissolved to beremoved using the following treatment bath (Desmear Bath manufactured byShipley Corporation). (hereinabove, the removal process)

<Treatment Condition of Desmear Bath> Bath composition of swellingprocess: MLB-211 20 vol % Cup-Z 10 vol % Bath temperature of swellingprocess: 80° C. Bath composition of roughening process: MLB-213A 10 vol% MLB-213B 15 vol % Bath temperature of roughening process: 80° C.

After the foregoing removal of the resin material was finished, cuttinginto a size of 3 cm×3 cm was carried out to obtain a filter for hydrogenproduction.

Evaluation of Hydrogen Production Filter

The filter thus produced was mounted in a reformer, and a mixture ofbutane gas and steam was supplied to the Pd alloy film of the filterunder the same condition as Example 1, thereby to measure COconcentrations and flow rates of hydrogen rich gas transmitted to theside of the porous base member of the filter. As a result, the COconcentrations immediately after the start of reforming up to a lapse of300 hours were 8 to 10 ppm which were extremely low, and the flow ratesof the hydrogen rich gas were 10 L/hour, and therefore, it was confirmedthat the hydrogen production filter produced by the present inventionwas excellent in durability and hydrogen transmission efficiency.

EXAMPLE 4

Production of Filter for Hydrogen Production

A filter for hydrogen production was produced like in Example 3 exceptthat a Pd alloy film (thickness: 0.2 μm) was formed by a sputteringmethod under the following condition instead of the electroless platingmethod in the underlayer forming process, thereby to obtain a conductiveunderlayer.

<Sputtering Condition> RF power: 500 W Argon gas pressure: 5.4 × 10⁻² Padc current: 2.5 AEvaluation of Hydrogen Production Filter

The filter thus produced was mounted in a reformer, and a mixture ofbutane gas and steam was supplied to the Pd alloy film of the filterunder the same condition as Example 1, thereby to measure COconcentrations and flow rates of hydrogen rich gas transmitted to theside of the porous base member of the filter. As a result, the COconcentrations immediately after the start of reforming up to a lapse of300 hours were 8 to 10 ppm which were extremely low, and the flow ratesof the hydrogen rich gas were 10 L/hour, and therefore, it was confirmedthat the hydrogen production filter produced by the present inventionwas excellent in durability and hydrogen transmission efficiency.

EXAMPLE 5

Production of Filter for Hydrogen Production

Like in Example 2, a plurality of through holes were formed in a SUS304member by etching using resist patterns as masks. However, after theetching process was finished, the resist patterns were not removed, butleft on the surface of the SUS304 member. (hereinabove, the etchingprocess)

Then, Ni strike plating (thickness: 0.2 μm) was applied under thefollowing condition to the inside of the through holes of the foregoingSUS304 member.

<Ni Strike Plating Condition> Bath composition: Nickel chloride 300 g/LBoric acid  30 g/L pH: 2 Liquid temperature: 55 to 65° C. Currentdensity: 10 A/dm²

Then, a Pd alloy film (thickness: 15 μm) was formed by electrolyticplating under the following condition so as to close the inside of thethrough holes using the resist patterns as masks. (hereinabove, the filmforming process)

<Film Forming Condition of Pd Alloy Film by Electrolytic Plating> Usingbath: Pd chloride plating bath (Pd concentration: 12 g/L) pH: 7 to 8Current density: 1 A/dm² Liquid temperature: 40° C.

Then, the resist patterns on the SUS304 member were removed using a 5%sodium hydroxide aqueous solution. (hereinabove, the removal process)

After the foregoing removal of the resist patterns was finished, cuttinginto a size of 3 cm×3 cm was carried out to obtain a filter for hydrogenproduction.

Evaluation of Hydrogen Production Filter

The filter thus produced was mounted in a reformer, and a mixture ofbutane gas and steam was supplied to the Pd alloy film of the filterunder the same condition as Example 1, thereby to measure COconcentrations and flow rates of hydrogen rich gas transmitted to theside of the porous base member of the filter. As a result, the COconcentrations immediately after the start of reforming up to a lapse of300 hours were 8 to 10 ppm which were extremely low, and the flow ratesof the hydrogen rich gas were 10 L/hour, and therefore, it was confirmedthat the hydrogen production filter produced by the present inventionwas excellent in durability and hydrogen transmission efficiency.

Comparative Example 2

Production of Filter for Hydrogen Production

Like in Example 2, a conductive base member was obtained by forming aplurality of through holes in a SUS304 member. Then, a Pd alloy filmhaving a thickness of 30 μm was bonded to the conductive base member viaan adhesive so as to be unified together, and thereafter, the adhesiveremaining in the through holes of the conductive base member was removedusing acetone. This unified composite was cut into a size of 3 cm×3 cmto obtain a filter for hydrogen production.

Evaluation of Hydrogen Production Filter

The filter thus produced was mounted in a reformer, and a mixture ofbutane gas and steam was supplied to the Pd alloy film of the filterunder the same condition as Example 1, thereby to measure COconcentrations and flow rates of hydrogen rich gas transmitted to theside of the porous base member of the filter. As a result, the COconcentrations were 8 to 10 ppm, which were extremely low and thusexcellent, immediately after the start of reforming up to a lapse of 300hours. However, after the lapse of 300 hours, peeling of the Pd alloyfilm was caused due to degradation of the adhesive underhigh-temperature and high-pressure conditions, and the CO concentrationwas increased to about 3% due to generation of cracks of the Pd alloyfilm or the like, and therefore, it was confirmed that durability wasbad.

EXAMPLE 6

Production of Thin Film Support Substrate

A SUS304 member having a thickness of 150 μm was prepared as a basemember, and a photosensitive resist material (OFPR manufactured by TokyoOhka Kogyo Co., Ltd.) was applied (film thickness: 7 μm (upon drying))to both surfaces of the SUS304 member by a dip method. Then, a photomaskhaving, in a pitch of 430 μm, a plurality of circular shading portionseach having a diameter of 390 μm was disposed on the resist applicationfilm on the side of the SUS304 member where columnar convex portions areformed, and a photomask having, in a pitch of 430 μm, a plurality ofcircular opening portions each having an opening size (opening diameter)of 100 μm was disposed on the resist application film on the oppositeside. The resist application films were exposed via the photomasks anddeveloped using a sodium hydrogencarbonate solution. By this, circularresists each having the diameter of 390 μm were formed in the pitch of430 μm on one surface of the SUS304 member, while a resist patternhaving the circular opening portions each having the opening size(opening diameter) of 100 μm was formed on an opposite surface.Incidentally, positioning was carried out such that each vertex of atriangle having as its vertexes the centers of the nearest threecircular resists (diameter: 390 μm) was located in a position of thecenter of gravity of a triangle having as its vertexes the centers ofthe nearest three opening portions of the resist pattern on the oppositeside via the SUS304 member.

Then, the SUS304 member was etched under the following condition usingthe foregoing resist patterns as masks. This etching was for formingcolumnar convex portions by half etching from one surface of the SUS304member, and simultaneously, forming through holes by etching from bothsurfaces, and a time required for the etching was six minutes.

<Etching Condition> Temperature: 50° C. Iron chloride concentration: 45Baume Pressure: 3 kg/cm²

After the foregoing etching process was finished, the resist patternswere removed using a sodium hydroxide solution, and washing in water wascarried out. By this, a thin film support substrate as shown in FIG. 5was obtained, wherein the columnar convex portions of a cylindricalshape having a diameter of 290 μm and a height of 60 μm were formed inthe pitch of 430 μm on one surface of the SUS304 member having athickness of 90 μm, and the through holes each having an openingdiameter of 70 to 100 μm were formed in the pitch of 430 μm in theSUS304 member at a portion where the columnar convex portions were notformed. In this thin film support substrate, an area of the columnarconvex portion non-formed portion occupying on the side where thecolumnar convex portions were formed, was about 50%.

Production of Filter for Hydrogen Production

On the surface of the thus produced thin film support substrate wherethe columnar convex portions were formed, an insulating film(polyethylene terephthalate film) having a thickness of 200 μm was stuckto be disposed (hereinabove, the disposing process).

Then, the following pretreatment was applied to the thin film supportsubstrate excluding top surfaces of the columnar convex portions(including the inside of the through holes) and to the sticking side ofthe insulting film, and thereafter, electroless plating was performedunder the following condition to form an electroless nickel platinglayer (thickness: 0.4 μm), thereby obtaining a conductive underlayer.(hereinabove, the underlayer forming process)

<Pretreatment>

alkaline degreasing→washing in water→chemical etching (in ammoniumpersulfate 200 g/L aqueous solution (20° C.±5° C.))→washing inwater→acid treatment (10% dilute sulfuric acid (ordinarytemperature))→washing in water→acid treatment (30% dilute hydrochloricacid (ordinary temperature))→dipping in sensitizer added liquid(composition: 0.5 g of Pd chloride, 25 g of stannous chloride, 300 mL ofhydrochloric acid, 600 mL of water)→washing in water

<Electroless Nickel Plating Condition> Bath composition: Nickel sulfate20 g/L  Sodium hypophosphite 10 g/L  Lactic acid 3 g/L Sodium citrate 5g/L Sodium acetate 5 g/L pH: 4.5 to 6.0 Liquid temperature: 50 to 65° C.

Then, electrolytic copper plating was applied to the conductiveunderlayer under the following condition to form a copper plating layerso as to fill up spaces formed between the columnar convex portionnon-formed surface of the thin film support substrate and the insulatingfilm, and the inside of the through holes of the thin film supportsubstrate. (hereinabove, the copper plating process)

<Copper Plating Condition> Using bath: Copper sulfate plating bathLiquid temperature: 30° C. Current density: 1 A/dm²

Then, the insulating film was peeled and removed from the thin filmsupport substrate, and a Pd alloy film (thickness: 3 μm) was formed byelectrolytic plating on the thin film support substrate (top surfaces ofthe columnar convex portions) and the copper plating layer after theremoval under the following condition. Incidentally, upon thiselectrolytic plating, the copper plating layer on the back side of thethin film support substrate was covered with an insulating film.(hereinabove, the film forming process)

<Film Forming Condition of Pd Alloy Film by Electrolytic Plating> Usingbath: Pd chloride plating bath (Pd concentration: 12 g/L) pH: 7 to 8Current density: 1 A/dm² Liquid temperature: 40° C.

Then, the insulating film was peeled and removed, and further, thecopper plating layer was removed by selective etching. (hereinabove, theremoval process)

After the foregoing removal of the copper plating layer was finished,cutting into a size of 3 cm×3 cm was carried out to obtain a filter forhydrogen production.

Evaluation of Hydrogen Production Filter

The hydrogen production filter thus produced was mounted in a reformer,and a mixture of butane gas and steam was supplied to the Pd alloy filmof the filter under the same condition as Example 1, thereby to measureCO concentrations and flow rates of hydrogen rich gas transmitted to theside of the porous base member of the filter. As a result, the COconcentrations immediately after the start of reforming up to a lapse of300 hours were 8 to 10 ppm which were extremely low, and the flow ratesof the hydrogen rich gas were 10 L/hour, and therefore, it was confirmedthat the hydrogen production filter produced by the present inventionwas excellent in durability and hydrogen transmission efficiency.

EXAMPLE 7

Production of Thin Film Support Substrate

Like in Example 6, a thin film support substrate of the presentinvention was produced.

Production of Filter for Hydrogen Production

On the surface of the thus produced thin film support substrate which ison the opposite side relative to the columnar convex portion formedside, an insulating film (polyethylene terephthalate film) having athickness of 200 μm was stuck to be disposed (hereinabove, the disposingprocess).

Then, electrolytic copper plating was applied to the surface of the thinfilm support substrate on the columnar convex portion formed side toform a copper plating layer (thickness: about 80 μm) on the thin filmsupport substrate so as to fill up the inside of the through holes andcover the columnar convex portions. The copper plating condition was thesame as in Example 6. (hereinabove, the copper plating process)

Then, the copper plating layer was flat-removed by grinding so as toexpose the top surfaces of the columnar convex portions and form thesame flat surface with the top surfaces. In this event, the groundsurface was smoothed as much as possible. (hereinabove, the flatteningprocess)

Then, a Pd alloy film (thickness: 3 μm) was formed on the foregoing flatsurface. The electrolytic plating condition for this Pd alloy film wasthe same as in Example 6. (hereinabove, the film forming process)

Then, the insulating film was peeled and removed, and further, thecopper plating layer was removed by selective etching. (hereinabove, theremoval process)

After the foregoing removal of the copper plating layer was finished,cutting into a size of 3 cm×3 cm was carried out to obtain a filter forhydrogen production.

Evaluation of Hydrogen Production Filter

The hydrogen production filter thus produced was mounted in a reformer,and a mixture of butane gas and steam was supplied to the Pd alloy filmof the filter under the same condition as Example 1, thereby to measureCO concentrations and flow rates of hydrogen rich gas transmitted to theside of the porous base member of the filter. As a result, the COconcentrations immediately after the start of reforming up to a lapse of300 hours were 8 to 10 ppm which were extremely low, and the flow ratesof the hydrogen rich gas were 10 L/hour, and therefore, it was confirmedthat the hydrogen production filter produced by the present inventionwas excellent in durability and hydrogen transmission efficiency.

EXAMPLE 8

Production of Thin Film Support Substrate

Like in Example 6, a thin film support substrate of the presentinvention was produced.

Production of Filter for Hydrogen Production

A resin layer was formed on the surface of the thus produced thin filmsupport substrate on the columnar convex portion formed side, byfilling/applying a resin material (AZ1111 manufactured by ShipleyCorporation) by squeezing so as to fill up the inside of the throughholes and cover the columnar convex portions. (hereinabove, the resinlayer forming process)

Then, the resin layer was flat-removed by grinding so as to expose thetop surfaces of the columnar convex portions and form the same flatsurface with the top surfaces. In this event, the ground surface wassmoothed as much as possible. (hereinabove, the flattening process)

Then, electroless plating was performed to form an electroless nickelplating layer (thickness: 0.4 μm) on the foregoing flat surface, therebyto obtain a conductive underlayer. The condition of the electrolessnickel plating was the same as in Example 6. (hereinabove, theunderlayer forming process)

Then, a Pd alloy film (thickness: 3 μm) was formed on the foregoingconductive underlayer. The electrolytic plating condition for this Pdalloy film was the same as in Example 6. Upon the electrolytic plating,the opposite surface relative to the Pd alloy film formation was coatedwith an insulating film. (hereinabove, the film forming process)

Then, the insulating film was peeled and removed, and further, the resinlayer was dissolved to be removed using the following treatment bath(Desmear Bath manufactured by Shipley Corporation). (hereinabove, theremoval process)

<Treatment Condition of Desmear Bath> Bath composition of swellingprocess: MLB-211 20 vol % Cup-Z 10 vol % Bath temperature of swellingprocess: 80° C. Bath composition of roughening process: MLB-213A 10 vol% MLB-213B 15 vol % Bath temperature of roughening process: 80° C.

After the foregoing removal of the resin layer was finished, cuttinginto a size of 3 cm×3 cm was carried out to obtain a filter for hydrogenproduction.

Evaluation of Hydrogen Production Filter

The hydrogen production filter thus produced was mounted in a reformer,and a mixture of butane gas and steam was supplied to the Pd alloy filmof the filter under the same condition as Example 1, thereby to measureCO concentrations and flow rates of hydrogen rich gas transmitted to theside of the porous base member of the filter. As a result, the COconcentrations immediately after the start of reforming up to a lapse of300 hours were 8 to 10 ppm which were extremely low, and the flow ratesof the hydrogen rich gas were 10 L/hour, and therefore, it was confirmedthat the hydrogen production filter produced by the present inventionwas excellent in durability and hydrogen transmission efficiency.

EXAMPLE 9

Production of Thin Film Support Substrate

Like in Example 6, a thin film support substrate of the presentinvention was produced.

Production of Filter for Hydrogen Production

Ni strike plating (thickness: 0.01 μm) was applied to a copper basemember having a thickness of 0.2 mm under the following condition.

<Ni Strike Plating Condition> Bath composition: Nickel chloride 300 g/LBoric acid  30 g/L pH: 2 Liquid temperature: 55 to 65° C. Currentdensity: 10 A/dm²

Then, a Pd alloy film (thickness: 3 μm) was formed on one surface of thecopper base member applied with the foregoing Ni strike plating. Theelectrolytic plating condition for this Pd alloy film was the same as inExample 6. Upon the electrolytic plating, the opposite surface relativeto the Pd alloy film formation was coated with an insulating film.(hereinabove, the film forming process)

Then, after peeling and removing the insulating film from the copperbase member, the foregoing Pd alloy film was brought into contact withthe top surfaces of the columnar convex portions of the thin filmsupport substrate and, by applying a heat treatment at 1000° C. for 12hours in a vacuum, the Pd alloy film and the top surfaces of thecolumnar convex portions were joined together by diffusion to therebydispose the copper base member. (hereinabove, the diffusion joiningprocess)

Then, the copper base member was removed by selective etching.(hereinabove, the removal process)

After the foregoing removal of the copper base member was finished,cutting into a size of 3 cm×3 cm was carried out to obtain a filter forhydrogen production.

Evaluation of Hydrogen Production Filter

The hydrogen production filter thus produced was mounted in a reformer,and a mixture of butane gas and steam was supplied to the Pd alloy filmof the filter under the same condition as Example 1, thereby to measureCO concentrations and flow rates of hydrogen rich gas transmitted to theside of the porous base member of the filter. As a result, the COconcentrations immediately after the start of reforming up to a lapse of300 hours were 8 to 10 ppm which were extremely low, and the flow ratesof the hydrogen rich gas were 10 L/hour, and therefore, it was confirmedthat the hydrogen production filter produced by the present inventionwas excellent in durability and hydrogen transmission efficiency.

INDUSTRIAL APPLICABILITY

As described above, the production method of the hydrogen productionfilter according to the present invention is suitable for producing ahydrogen production filter that is used in a reformer of a fuel cell soas to be capable of stably producing high purity hydrogen gas.

1. A production method of a hydrogen production filter, characterized bycomprising a through hole closing step of attaching a metal plate to onesurface of a conductive base member having a plurality of through holesby the use of a magnet, a copper plating step of forming a copperplating layer on the conductive base member and said metal plate exposedwithin the through holes, from the side of said conductive base memberwhere said metal plate is not attached, thereby to fill up said throughholes, a film forming step of forming a Pd alloy film by plating on thesurface of said conductive base member after removal of said metalplate, and a removal step of removing said copper plating layer byselective etching.
 2. A production method of a hydrogen productionfilter according to claim 1, wherein the Pd alloy film is formed byelectrolytic plating in said film forming step.
 3. A production methodof a hydrogen production filter according to claim 1, wherein, in saidfilm forming step, thin films of respective components composing a Pdalloy are first stacked in layers by plating, then a heat treatment isapplied thereto to form the Pd alloy film by diffusion of thecomponents.
 4. A production method of a hydrogen production filteraccording to claim 1, wherein said conductive base member is a ferritestainless substrate.
 5. A production method of a hydrogen productionfilter according to claim 1, wherein said metal plate is a ferritestainless substrate.